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Rollup merge of #120929 - long-long-float:wrap-dyn-in-suggestion, r=fmease

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Wrap dyn type with parentheses in suggestion

Close #120223

Fix wrong suggestion that is grammatically incorrect.
Specifically, I added parentheses to dyn types that need lifetime bound.

```
help: consider adding an explicit lifetime bound
  |
4 |     executor: impl FnOnce(T) -> (dyn Future<Output = ()>) + 'static,
  |                                 +                       +++++++++++
```
This commit is contained in:
León Orell Valerian Liehr 2024-04-23 17:25:14 +02:00 • committed by GitHub
commit 80f2b91b20
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10 changed files with 286 additions and 62 deletions
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46
compiler/rustc_hir/src/hir.rs
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@ -644,13 +644,49 @@ impl<'hir> Generics<'hir> {
})
}
pub fn bounds_span_for_suggestions(&self, param_def_id: LocalDefId) -> Option<Span> {
/// Returns a suggestable empty span right after the "final" bound of the generic parameter.
///
/// If that bound needs to be wrapped in parentheses to avoid ambiguity with
/// subsequent bounds, it also returns an empty span for an open parenthesis
/// as the second component.
///
/// E.g., adding `+ 'static` after `Fn() -> dyn Future<Output = ()>` or
/// `Fn() -> &'static dyn Debug` requires parentheses:
/// `Fn() -> (dyn Future<Output = ()>) + 'static` and
/// `Fn() -> &'static (dyn Debug) + 'static`, respectively.
pub fn bounds_span_for_suggestions(
&self,
param_def_id: LocalDefId,
) -> Option<(Span, Option<Span>)> {
self.bounds_for_param(param_def_id).flat_map(|bp| bp.bounds.iter().rev()).find_map(
|bound| {
// We include bounds that come from a `#[derive(_)]` but point at the user's code,
// as we use this method to get a span appropriate for suggestions.
let bs = bound.span();
bs.can_be_used_for_suggestions().then(|| bs.shrink_to_hi())
let span_for_parentheses = if let Some(trait_ref) = bound.trait_ref()
&& let [.., segment] = trait_ref.path.segments
&& segment.args().parenthesized == GenericArgsParentheses::ParenSugar
&& let [binding] = segment.args().bindings
&& let TypeBindingKind::Equality { term: Term::Ty(ret_ty) } = binding.kind
&& let ret_ty = ret_ty.peel_refs()
&& let TyKind::TraitObject(
_,
_,
TraitObjectSyntax::Dyn | TraitObjectSyntax::DynStar,
) = ret_ty.kind
&& ret_ty.span.can_be_used_for_suggestions()
{
Some(ret_ty.span)
} else {
None
};
span_for_parentheses.map_or_else(
|| {
// We include bounds that come from a `#[derive(_)]` but point at the user's code,
// as we use this method to get a span appropriate for suggestions.
let bs = bound.span();
bs.can_be_used_for_suggestions().then(|| (bs.shrink_to_hi(), None))
},
|span| Some((span.shrink_to_hi(), Some(span.shrink_to_lo()))),
)
},
)
}